This study is divided into two parts. One secretion, comprising two-thirds of time and effort, examines the neurotoxic properties of a number of high-volume, chemically and biologically related, aromatic hydrocarbons implicated as causative agents of neurological and behavioral disorders in workers chronically exposed to organic solvents. These aromatic hydrocarbons share the remarkable property of inducing a blue-green discoloration of urine and tissue following prolonged high-level exposure. Based on our studies of tetralin derivatives, one which discolors tissue blue and causes widespread neuronal and myelin degeneration, the chromogenic and neurotoxic propertiesof these compounds appear to be linked, non0chromogenic derivatives also being non-neurotoxic. The ortho, meta (both chromogenic) and para (non-chromogenic) isomers of diethyl benzene will be used to determine the strucutre/activity interrelationships between chromogenicity and chronic neurotoxicity. The chromogenic and chronic neurotoxic properties of chemically related aromatic hydrocarbons --- diphenyl, indane and naphthalene derivatives (known human neurotoxins), and decalin --- will be compared with those of tetralin using appropriate behavioral, electrodiagnostic (nerve conduction studies) and morphological (light and electron microscopy) techniques. The second section, comprising one-third of time and effort, examines the feasibility of employing somato-sensory evoked potentials (SEP) for the detection of peripheral neuropathy in workers occupationally exposed to neurotoxic chemicals. This novel approach has developed directly from our previous animal studies with occupational neurotoxins demonstrating that certain neural pathways inthe central and peripheral nervous system selectively and concurrently undergo degeneration. The SEP will be compared with other, more conventional methods for detecting subclinical and overt neuropathy (neurological exam, nerve conduction, electromyography, OptaconR) in order to develop a program to screen vulnerable workers for neurotoxic disease in the factory setting.